In a helicopter rotor grip assembly, pitch change linkages are utilized for interconnecting the rotor grip and a control system for the rotor blades. The pitch change link length is manually adjustable in order to track the rotor properly so that all three blades of the helicopter turn in the same tip path plane. Each blade is adjustable independently of the other two blades to increase or decrease the blade pitch. For rotor blade tracking and balance, the pitch change links are adjusted to increase or decrease the length of the link thereby changing the pitch of the rotor blade.
Typically in the adjustment process, the maintenance personnel will mentally note, or a make a written record of the adjustment made to a pitch change link. Subsequently, when additional changes must be made to the blade pitch, the maintenance personnel may not recall whether a previous change was an increase or a decrease in the pitch change link length, and therefore inaccuracies and more frequent adjustments of the pitch change link are required in order to properly adjust the pitch of the rotor blades. Current techniques for changing the length of the pitch change link provide no reliable and accurate scheme for determining or recording changes as adjustments of the pitch change link are made during rotor blade tracking and balance. The maintenance personnel may arbitrarily rotate the pitch change link by a portion of a turn, but not be able to duplicate this same change for subsequent link adjustment. Further, it is undesirable to remove a pitch change link from the helicopter rotor assembly after each adjustment for measuring the length of the pitch change link. Such a procedure is time consuming, and further results in inaccuracies during the rotor blade tracking and balance procedure.
A need has thus arisen for a pitch change link that allows for a direct and accurate reading of changes in length for use during rotor blade tracking and balancing without removal of the pitch change link from the helicopter hub assembly. A need has further arisen for a calibration device for a pitch change link that automatically displays reference indicia to indicate a corresponding length of the pitch change link.